Choosing fruits and vegetables to optimize your diet

Unfortunately, while increasing your fruits and vegetables is a big step towards optimzing you diet, in modern times care must be taken in selecting the most nutritious fruits and vegetables as well. Modern popular varieties of fruits and vegetables have been bred for larger yields, better taste (i.e. higher sugar and lower levels of bitter phytonutrients) and easier processing. Little care has been taken to ensure that these varieties are as nutrient-rich as their ancient ancestors. In fact, it has been estimated that of all the factors leading to nutrient decline, plant breeding is the largest culprit.

Compared with wild plants, most modern varieties are lower in protein, fiber, vitamins, minerals and essential fatty acids. Additionally, modern varieties often have higher levels of sugar than ancient varieties. In a surprising 2011 study involving 46 overwight men, the addition of 300 grams of golden delicious apple per day resulted in increased triglycerides and VLDL levels. An increase in triglycerides typically results from refined carbohydrates, however in this study the golden delicious apple acted in a similar manner.

Just choosing fruits and vegetables is no longer enough. For maximal health, you must take care to also choose the most nutritious options. In general, this means that you should look for the brightest darkest colors you can find:

• Greens - Choose loose-leaf dark red, green and purple for the maximum nutrient punch. Head lettuce and light green lettuce, like iceberg and even romaine, are the least nutritious choices. Avoid pre-chopped bagged mixes of wilted browning lettuce. Lettuce begins to lose nutrients when it is chopped, and wilted brown edges indicate that it was prepared long enough ago to lose significant nutrients. Serve greens with a small amount of fat, like olive oil, butter or avocado, to help with absorption of the fat soluble nutrients and carotenoids.

• Corn - Choose dark yellow kernels over white kernals for the most carotenoids, including higher levels of beta-carotene, lutein and zeaxanthin. If you can find it, blue corn or purple corn contains significantly more anthocyanins.

• Potatoes - Potatoes with the dark purple, red or blue skin and/or flesh contain more antioxidants than yellow potatoes. Look for new potatoes, which have less of an effect on blood sugar than mature ones. Russet potatoes make the best third choice as they are higher in phytonutrients compared to white potatoes, but do contain a significant amount of starch which can have an effect on blood sugar. A better option is the sweet potato. Look for one with dark orange flesh, which has a much lower effect on blood sugar and almost twice the antioxidant value of a russet potato.

• Carrots - Look for purple or red carrots, which contain significantly more anthocyanins than the more common orange carrot. When choosing carrots, your best bet is organic whole carrots. Carrot skin and the outer flesh just under the skin contain the most carotenoids. Just scrub them well and eat whole, rather than peeling them, for the most nutrition. Limit your consumption of “baby carrots” which are higher in the sugary less-nutritious inner core. For maximum nutrient release, cook carrots and serve with a small amount of fat to help with the carotenoid absorption.

• Beets - Look for dark red beets for the highest concentration of betalain, a compound with cell protecting and cardiovascular support properties. White, yellow or striped beets contain significantly lower levels. Ideally, looks for beets with greens attached and eat the greens as well. Beet greens are on par with kale for nutritional value.

• Tomatoes - Choose deep red tomatoes over yellow or green tomatoes. In addition, the smaller sized options, like grape tomatoes or cherry tomatoes, contain higher levels of lycopene. Cooking tomatoes, think tomato sauces and even ketchup, helps convert the nutrients into more bioavailable forms. 

• Legumes - Lentils, black beans and dark red kidney beans contain the hgiher levels of antioxidants, while chickpeas and green peas contain the least. If you are looking for a more nutritional option of green peas, choose ones with edible pods. 

• Cruciferous vegetables - Look for the freshest broccoli, Brussels sprouts, cabbage, cauliflower and kale you can find as the nutrients begin to degrade shortly after picking. Pre-trimmed options will be less nutritious than whole heads. Red cabbage is higher in antioxidants compared to green cabbage. Purple or green cauliflowers (usually found at farmer’s markets) contain more antioxidants compared to white caulflower, however the white version is still a great source of the cancer-fighting compounds glucosinolates.

• Apples - Look for dark red (or green as in the case of Granny Smith) uniformly colored apples for the most nutritious option. The best choices include Braeburn, Cortland, Fuji, Gala, Granny Smith, HoneyCrisp and Red Delicious. Apples with pale skin have much lower nutrient levels, including Golden Delicious, Ginger Gold, Empire and Pink Lady. Make sure to eat the skin, where most of the nutrients are found. Choose organic apples to limit pesticide exposure.

• Berries - Berries are one of the most nutritious foods you can buy. Among the group, blueberries and blackberries with their dark color signify that they are the richest sources of anthocyanins. Cranberries and dark red raspberries are also great options. If you can find ripe strawberries, usually at a Farmer’s market or pick-your-own facility, they also make a good choice. Unriped strawberries, such as that usually found in a grocery store, have much lower levels of vitamin C, quercetin and anthocyanins.

• Stone fruits - Look for fully ripe, dark-colored peaches, nectarines, apricots, plums and cherries. Purchasing these fruits when they are ripe ensures that the nutrients have had time to fully develop. Peaches and nectarines are the exception to the bright color rule; white-fleshed varieties are actually richer in phytonutrients compared to yellow-fleshed varieties. Again, make sure to eat the skin, where most of the nutrients are found, and choose organic to limit pesticide exposure.

• Grapes - Choose dark purple or red grapes for the most nutritious option, particularly Concord grapes. Pale green grapes are the least nutritious option. Currants, made from Black Corinth grapes, have more antioxidants than traditional or golden raisins, which are both typically made from green grapes.

• Citrus fruits - Choose citrus fruit with the darkest-colored flesh for maximum phytonutrient content, including Cara Cara oranges, blood oranges, Valencias, mandarins, tangelos and red or pink grapefruits. Naval oranges are also good choices. Look for large-sized oranges with deep orange flesh. The skin can be mis-leading as fruits are often treated with ethylene gas to induce a bright orange color. At the grocery store, look for oranges that range in color from yellow to deep orange and choose the darkest ones you can find. If the oranges are all a deep orange color, look for the largest frruit in the display, which is a sign it has been allowed to ripen longer on the tree.

References 

1. Davis DR. Declining Fruit and Vegetable Nutrient Composition: What is the Evidence?. HortScience. Feb 2009. 44(1): 15-19. 
2. Vafa MR, Haghighhatjoo E, Shidfar F. Effects of apple consumption on lipid profile of hyperlipidemic and overweight men. Int J Prev Med. 2011 Apr; 2(2): 94-100. 
3. Robinson, J. (2013) Eating on the Wild Side. New York, NY: Little, Brown and Company.

Calcium: Friend or Foe?

What a hit calcium has taken in the news lately. Another recent study suggests that women with calcium intakes of greater than 1,400 mg per day were more than twice as likely to die compared with women taking between 600 and 999 mg (1). The study was published in the British Medical Journal and looks at women in the Swedish mammography cohort. Drawbacks of the study are that it is a population study, looking at what the women were doing rather than carefully controlling the calcium levels to determine a cause and effect. Additionally, the study did not control for hormone replacement therapy use.

That being said, the research against calcium seems to be mounting. In an analysis of a double-blind trial intended to assess the effect of calcium on fracture incidence, the incidence of cardiovascular events (including myocardial infarction, stroke or sudden death) was 47% higher in women who received 1,000 mg per day of calcium for 5 years.(2) It is important to keep in mind that the study was not designed to study cardiovascular disease, and confounding factors were not equally distributed across both groups. For example, the supplemented group had a greater number of individuals with high cholesterol and smokers. Both of these factors increase the risk of a cardiovascular event. Another analysis of the National Institutes of Health (NIH)-AARP (formerly known as the American Association of Retired Persons) Diet and Health Study found that supplemental calcium was associated with heart disease death in men.(3) However, this study was again not designed to look at cardiovascular disease and suffers from the same confounding concerns of the first study. Another study, the EPIC-Heidelberg study, suggests that dietary calcium may be more better than supplemental calcium.(4) In this study, participants taking 820 mg of calcium per day from diet and supplements had a significantly reduced risk of myocardial infarction compared to individuals in the lowest level of intake (less than 513 mg per day), however users of calcium supplements had an increased risk compared to non-supplement users. Clinicians have theorized that the risk may be due to large boluses of calcium, unlike the smaller intakes that occur with dietary calcium, or that starting large supplemental doses of calcium may cause abrupt changes in serum calcium concentration leading to adverse effects.(5) The increased risk could also be due to calcium induced magnesium or other trace element depletions. Other analyses, using data from the Women’s Health Initiative and the Framingham Offspring Study do not show increased risk of heart disease or coronary calcification from calcium supplementation. (6,7)

Weighing both the importance of calcium for bone and the potential concerns, it seems wise to ensure that intake of calcium from the diet and supplements should be between 750 and 1200 mg per day, and limited to less than 1,500 mg per day. Limiting calcium to 1,000 mg per day may be desired, as well as choosing highly absorbable forms of calcium, such as calcium citrate or calcium citrate/malate, and ideally supplementing with 300 mg of calcium at a time. It seems wise to increase the amount of calcium in the diet, limiting supplemental calcium correspondingly. Additionally serum vitamin D levels should be checked and maintained in the optimal range.

Sources of calcium include dairy products like milk, yogurt and cheese (which contain approximately 300 mg per serving), sardines or salmon with bones (which contain approximately 250-300 mg calcium per 3 oz. serving), nuts or seeds (which contain approximately 40-70 mg calcium per 1 oz serving), dark green leafy vegetables (which contain approximately 50-110 mg per 1/2 cup cooked serving), and calcium supplements.

References

1. Michaelsson K, Melhus H, Warensjo E, et al. Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study.BMJ. 2013; 346: 228.
2. Bolland MJ, Barber PA, Doughty RN, et al. Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial. BMJ. 2008 Feb 2;336(7638):262-6.
3. Xiao Q, Murphy RA, Houston DK, et al. Dietary and Supplemental Calcium Intake and Cardiovascular Disease Mortality: The National Institutes of Health-AARP Diet and Health Study.JAMA Intern Med. 2013 Feb 4:1-8.
4. Kuanrong L, Kaaks R, Linseisen J, Rohrmann S. Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition study (EPIC-Heidelberg). Heart 2012;98:920-925.
5. Bolland MJ, Grey A, Avenell A, Gamble GD, Reid IR. Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women's Health Initiative limited access dataset and meta-analysis. BMJ. 2011 Apr 19;342:d2040. 
6. Samelson EJ, Booth SL, Fox CS, et al. Calcium intake is not associated with increased coronary artery calcification: the Framingham Study. Am J Clin Nutr. 2012 Dec;96(6):1274-80.
7. Prentice RL, Pettinger MB, Jackson RD, et al. Health risks and benefits from calcium and vitamin D supplementation: Women's Health Initiative clinical trial and cohort study. Osteoporos Int. 2013 Feb;24(2):567-80.

Potassium and Acid/Base Balance for Bone Health

Potassium is the third most abundant mineral in the body. It is a critical nutrient in the body, playing a main role in cell to cell communication. Potassium is also critical for plant growth, being one of the key nutrients used in even the most basic of fertilization programs. Potassium accumulates in plant cells, making fruits and vegetables a good dietary source.

Several studies suggest that potassium citrate combined with calcium and vitamin D may support healthy bone. In a randomized, double-blind placebo controlled trial involving 201 elderly healthy men and women, 60 mEq (2,345 mg) of potassium citrate daily increased bone mineral density at the lumbar spine by 1.7 after 24 months.  These effects are believed to be due to the alkalinizing effect of potassium citrate (potassium chloride does not have the same effect).  Potassium citrate reduces dietary acidity, helping to facilitate calcium absorption and decrease urinary calcium loss.

Bone is a dynamic tissue that is constantly being reshaped by osteoblasts, bone-building cells that are responsible for laying down protein and minerals that make up the bone matrix, and osteoclasts, which break down older tissue critical for maintenance and repair.  An acidic environment inhibits osteoblast function and increases osteoclast activity skewing the bone remodeling process towards breakdown, while an alkaline environment stimulates bone-building and lessens bone breakdown.  

Fruits and vegetables provide potassium and promote an alkaline environment to support healthy bone, while animal protein and grains generate metabolic acids. The breakdown of amino acids and phosphate generates hydrogen ions (increasing acidity), while the breakdown of citrate produces bicarbonate (increasing alkalinity). Research suggests that a normal Western diet generates approximately 1 mEq of acid per day. This metabolic acid load requires neutralization by bicarbonate ions and mineral ions from bone. Metabolic acidosis has been associated with increased calcium excretion believed to be from the bone tissue.

Choosing a diet rich in potassium-rich fruits and vegetables and supplementing with 200-1,200 (5 mEq-30 mEq) potassium citrate can promote an alkaline environment to support healthy bone. However, it is not advised to supplement with larger amounts of potassium citrate. Large doses of potassium can cause diarrhea, and high levels of potassium in the blood can cause potentially fatal cardiac arrhythmia.

Other nutrients that are important for bone health include calcium, vitamin D, magnesium, vitamin K and trace minerals. 

References

1. Jehle S, Hulter HN, Krapf R. Effect of Potassium Citrate on Bone Density, Microarchitecture, and Fracture Risk in Healthy Older Adults without Osteoporosis: A Randomized Controlled Trial. J Clin Endocrinol Metab. 2013 Jan;98(1):207-17.
2. Bushinsky DA. Acid-base imbalance and the skeleton. Eur J Nutr. 2001; 40:238–244.
3. Kurtz I, Maher T, Hulter HN, Schambelan M, Sebastian A. Effect of diet on plasma acid-base composition in normal humans. Kidney Int. 1983 Nov;24(5):670-80.
4. Sebastian A, Harris ST, Ottaway JH, Todd KM, Morris RC Jr. Improved mineral balance and skeletal metabolism in postmenopausal women treated with potassium bicarbonate. N Engl J Med. 1994 Jun 23;330(25):1776-81.
5. Jehle S, Zanetti A, Muser J, Hulter HN, Krapf R. Partial neutralization of the acidogenic Western diet with potassium citrate increases bone mass in postmenopausal women with osteopenia . J Am Soc Nephrol. 2006 Nov;17(11):3213-22.
6. Sakhaee K, Maalouf NM, Abrams SA, Pak CY. Effects of potassium alkali and calcium supplementation on bone turnover in postmenopausal women. J Clin Endocrinol Metab. 2005 Jun;90(6):3528-33.

Keep 5-MTHF in Dietary Supplements

A new proposed legislation is calling for dietary supplement companies to no longer be able to list “folate” on their labels. This legislation would force supplement companies to offer only folic acid. Why is this harmful for the average consumer?

Folate is a general term referring to a family of compounds, including folic acid. Good sources of dietary folate include legumes and dark green leafy vegetables. These foods contain folate primarily in the activated form, (L)-5-methyl-THF (5-MTHF). This activated folate is the coenzyme that participates in numerous methylation reactions, including the synthesis and repair of DNA and cell membrane function. Proper methylation, utilizing 5-MTHF, plays a key role in cell division and growth, particularly important for pregnancy and infancy, as well as healthy red blood cell development, detoxification, immune function, cardiovascular health and mood.

Folic acid is just one member of the folate group. It is used in dietary supplements because it is so stable, but rarely occurs in nature. Unlike 5-MTHF, folic acid requires enzymatic reduction in order to function as a methyl donor. While synthetic folic acid can be converted to 5-MTHF in the body, this process requires the enzyme 5,10-methylene tetrahydrofolate reductase (MTHFR). Estimates indicate that up to 30-40% of the population can have genetic variations that impair MTHFR from effectively activating folic acid to 5-MTHF.

This means that up to a third of the population may not be getting enough folate, particularly if they are not eating legumes or dark green leafy vegetables regularly. Additionally, these individuals may have an excess of unmetabolized folic acid. Some research has suggested that large amounts of unmetabolized folic acid can increase risk of prostate, lung or colon cancer. For these individuals, supplemental folate must be in the form of 5-MTHF.

Please send a letter to the FDA today telling them that dietary supplement companies should be allowed to use 5-MTHF!

References

1. Bailey SW, Ayling JE. The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake. Proc Natl Acad Sci U S A. 2009;106(36):15424-9.
2. Ebbing M, Bønaa KH, Nygård O, et al. Cancer incidence and mortality after treatment with folic acid and vitamin B12. JAMA. 2009 Nov 18;302(19):2119-26. 
3. Figueiredo JC, Grau MV, Haile RW, et al. Folic acid and risk of prostate cancer: results from a randomized clinical trial. J Natl Cancer Inst. 2009 Mar 18;101(6):432-5.
4. Kelly P, McPartlin J, Goggins M, et al. Unmetabolized folic acid in serum: Acute studies in subjects consuming fortified food and supplements. Am J Clin Nutr. 1997;65:1790-95.
5. Troen AM, Mitchell B, Sorensen B, et al. Unmetabolized folic acid in plasma is associated with reduced natural killer cell cytotoxicity among postmenopausal women. J Nutr. 2006;136(1):189-94.
6. Sharp L, Little J. Polymorphisms in genes involved in folate metabolism and colorectal neoplasia: a HuGE review. Am J Epidemiol. 2004; 159(5):423-43.

Multivitamins in the News

Multivitamins have been in the news lately, as a few trials have failed to show improvements in cancer and cardiovascular disease. I think this is an unfair assessment. No one ever said that multivitamins could improve cancer or cardiovascular disease. Instead they provide nutrients to fill in the gaps. Subjects might have had subtle differences in energy level or mood, but it is unfair to think that a multivitamin might prevent cancer.

In a press release from the Council of Responsible Nutrition (CRN), Drs. MacKay and Wong state "None of the three studies suggested that the medical community should abandon using and recommending MVMM supplements, yet that’s what the editorial authors called for. In fact, as  observed in their review, the report from the U.S. Preventive Services Task Force actually called for additional research and innovative research methodologies to study the effects of nutrients. Further, according to the CRN scientists, the AIM editorial missed the point of why most consumers take vitamins—not for preventing chronic disease, but instead for the very real nutrient shortfalls found in most Americans’ diets.

“Recent government research shows that a large portion of Americans fall below the estimated average requirement (EAR) for certain nutrients, specifically vitamins A, C, D, and E and magnesium and calcium, even when nutrient intake from diet, fortified foods, and supplements is considered,” Drs. MacKay and Wong emphasize in their review. “Intake of some nutrients is low enough to be a public health concern. These include potassium, dietary fiber, calcium, and vitamin D, along with iron, folate, and vitamin B12 for specific population groups.""