It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term retirement investors' portfolios.

Let's learn about some of Zacks' highest ranked mutual funds with low fees you may want to consider.

If you are looking to diversify your portfolio, consider

Janus Henderson Global Life Science I

(JFNIX). JFNIX is part of the Sector - Health category, offering investors a focus on the healthcare industry, one of the largest sectors in the American economy. This fund is a winner, boasting an expense ratio of 0.77%, management fee of 0.64%, and a five-year annualized return track record of 14.09%.

Royce PA Mutual Fund Institutional

(RPMIX). Expense ratio: 0.91%. Management fee: 0.76%. RPMIX is a Small Cap Value mutual fund option, which typically invest in companies with market caps under $2 billion. This fund has managed to produce a robust 12.41% over the last five years.

TIAA-CREF Large Cap Value Retail

(TCLCX): 0.71% expense ratio and 0.4% management fee. TCLCX is a Large Cap Value mutual fund, which invests in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. With a five-year annual return of 12.47%, this fund is a well-diversified fund with a long track record of success.

We hope that your investment advisor (if you use one) has you invested in one or all of the top-ranked mutual funds we've reviewed. But if that isn't the case, it might be time to have a conversation or reconsider this vitally important relationship.

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